EP1326713B1 - Flotation device - Google Patents

Abstract

A flotation device for separating materials or mixtures of materials from suspensions includes a reaction and mixing space (18) with eccentric inlet (16) for the mixture of suspension particles with gas bubbles and for further transport into at least one centrally arranged vertical suspension distribution tube (26), wherein the suspension distribution tube (26) and the clarified fluid collecting tube (48) are arranged adjacently, the plates (30) surround the suspension distribution tube (26) and the clarified fluid collecting tube (48) in an annular manner; and every second annular plate space (31) between adjacent plates (30) is connected to the suspension distribution tube (26) and every other space (31) between plates is connected to the clarified fluid collecting tube (48), so that the flow takes place out of one space (31) between plates from the inside towards the outside to the separating space (32), and subsequently into an adjacent space (31) between plates from the outside towards the inside. The substantive advantages of the invention are in that by combination of the plate arrangement with the eccentrically loaded reaction and mixing space, improved flocculation and thus better processing values are obtained in the filtrate. Better separation values are obtained by separation using the double-plate principle.

Description

The invention relates to a flotation device for the separation of substances or mixtures of substances from suspensions to form at least one rich and a low-fluff fraction, with several in a flotation tank above each other to parent, rotationally symmetric lamellae, wherein the low-carbon fraction enters during the separation process in blade interstices between the slats and a clear fluid Gets collected and horizontally outside the slats, a vertically extending annular separation space is formed, which communicates with a provided above the slats drain for the rich fraction.

From US 3,182,799 a flotation device with a rectangular outline is known, in which upward slats are present, wherein in the space between two slats above a suspension inlet and below a clear fluid outlet are provided, between the inlet and outlet short baffles are present. This arrangement has the disadvantage that due to the dimensioning of the baffles especially at high hydraulic load (high pressures or flow rates), a "short-circuit current" from the inlet to the process is created, which causes drastically deteriorated efficiencies in the separation. Furthermore, the cleaning of the plant, as this particular in the paper industry in the color change is required, very expensive due to the separate supply lines.

Proceeding from this, the present invention seeks to provide a generic flotation, which avoids the disadvantages mentioned above and is characterized in particular by an effective separation of the desired substances of the suspension in a low-material and a rich fraction.

This object is achieved by the features specified in claim 1. Advantageous developments emerge from the subclaims.

The most significant advantages of the invention are that compared to horizontal flotation devices, the installation area is reduced and thus the flotation performance per installation area is greater. The combination of the lamellar arrangement with the eccentrically charged reaction and mixing chamber results in improved flocculation and thus better process values in the filtrate. The deposition by means of the double-lamellar principle results in better deposition values.

Fig. 1:

einen schematischen Axialschnitt durch eine erste Ausführungsform der erfindungsgemäßen mit einer Flotationsvorrichtung;

Fig. 2:

drei schematische Querschnitte durch die Flotationsvorrichtung gemäß Figur 1 entlang der Linien A-A, B-B und C-C;

Fig. 3:

einen schematischen Axialschnitt durch eine zweite Ausführungsform der erfindungsgemäßen mit einer Flotationsvorrichtung;

The invention will be further explained with reference to the accompanying drawings. Showing:

Fig. 1:

a schematic axial section through a first embodiment of the invention with a flotation device;

Fig. 2:

three schematic cross sections through the flotation device according to Figure 1 along the lines AA, BB and CC;

3:

a schematic axial section through a second embodiment of the invention with a flotation device;

FIG. 1 shows, in a schematic axial section, a first embodiment of the invention, that is to say a flotation device 10a . In Figures 2a, 2b and 2c are three cross-sections through the flotation device 10a along the lines AA (Figure 2a). BB (Figure 2b) and CC (Figure 2c).

With reference to Figures 1 and 2, the flotation device 10a consists essentially of a round flotation tank 12 at the lower end of the suspension inlet and the clear fluid outlet and at the top end of the drain is intended for the flotate. As indicated by the flanges 14 , the flotation tank may be constructed of a plurality of segments.

In detail, a suspension feed 16 is provided in the lower region of the flotation device 10a , which opens into a double conical reaction and mixing chamber 18 eccentrically. In the conical bottom region of the reaction and mixing chamber 18 , a sediment outlet 20 is provided, which is connected to a sediment conduit 22 which is closed by a timed sediment valve 24 .

The upper cone of the reaction and mixing chamber 18 opens into at least one suspension distribution tube 26 arranged vertically approximately centrally in the flotation tank 12 , which has a multiplicity of preferably slit-like suspension outlets 28 into the interior of the flotation tank 12 .

In the flotation tank 12 and the at least one Suspensionsverteilrohr 26 annularly surrounding a plurality of conically widening upward annular slats are arranged, of which each second slat 30a is made shorter in the radial direction and each other slat 30b longer. The suspension outlets 28 open into first annular lamellae 31 a , each of which is bounded below by a long lamella 30 b and above by a short lamina 30 a . Arranged in alternation with the first lamination annular spaces 31a are second lamellar annular spaces 31b , each of which is bounded at the bottom by a short lamella 30a and at the top by a long lamella 30b .

Radially outside the long fins 30b extends to the wall of the flotation tank 12, an annular separation space 32 which communicates with a provided in the upper part of the flotation tank 12 Flotatsammelraum 34 . There, a Räumpaddelvorrichtung 36 is mounted on the flotation tank 12 , the more about two roller assemblies 38a, 38b and endless belts 40 circumferential Räumpaddel 42 include, which dip into the Flotatsammelraum 34 and lead to a circumferential Flotatabführrinne 461 .

The second finned annular spaces 31b preferably have slot-like clear fluid outlets 46 on the inside, via which a connection to at least one clear fluid collecting pipe 48 is formed. The at least one clear fluid collection tube 48 in turn opens into a clear fluid reservoir 50 , which communicates with a clear fluid discharge port 52 , which is provided with a control valve, not shown, to adjust the liquid level in the flotation tank 12 .

As can be seen from Fig. 2b, several suspension distribution tubes 26 and a plurality of clear fluid collection tubes 48 are combined to form a cell tube consisting of a plurality of circular cross-section shaped parallel tubes, each second sector tube being a suspension distributor tube 26 and each other sector tube being a clear fluid collection tube 48 forms. The cell tube is circular in cross-section in the illustrated embodiment. It may alternatively be polygonal, in particular square, and in particular four square arranged side by side in turn square tubes, of which two opposite tubes suspension distribution tubes 26 and the other tubes clear fluid collecting tubes 48 are.

The fins 30 are shown in Figure 2b with a circular cross-section. Other shapes such as polygons, especially a square, may also be used. The shorter fins 30a are about 5% to 40%, preferably 10% to 20%, shorter than the longer fins 26b .

The separation space 26 preferably has a width which corresponds to between 10% and 30% of the length of the longer lamellae 30b .

In operation, a suspension, preferably water, which may also contain heavy particles, on the suspension feed 16 eccentrically introduced tangentially into the reaction and mixing chamber 18 . The suspension can either be mixed with gas bubbles before entry into the reaction and mixing chamber 18 or shortly afterwards and / or chemical or physical flocculation aids can be added. Due to the tangential inflow of the suspension into the reaction and mixing chamber 18, there is an effective separation of the heavy parts, which sink downwards and are discharged via the sediment outlet 20 .

From the reaction and mixing chamber 18 , the suspension mixed with flocculants and / or gas bubbles flows into the suspension distribution tube 26 arranged above, and from there via the suspension outlets 28 into the first annular disc spaces 31a . The suspension then flows with continuous deceleration radially outwards and upwards and enters the separation space 32 . In this case, there is increasingly a separation of the suspension in clear fluid and the substances to be separated, ie solids, dissolved and partially dissolved substances. While the substances to be separated flow upwards in the separation space to the flotation collection chamber 34 , the mass of the clear fluid flows into the second lamella annular spaces 31b , which are arranged alternately with the first lamella annular spaces 31a . Through the laminar annular spaces 31b , the clear fluid flows obliquely downwards and inwards, with a further separation of the solids, dissolved and partially dissolved substances, which flow back upwards and outwards to the separation space 32 . The clear fluid flows via the slit-type clear fluid outlets 46 into the clear fluid collection pipe 48 and thence to the clear fluid discharge line 50 where it is discharged from the flotation device 10a via the controlled-fluid clearing discharge port 52 .

In Fig. 3, a second embodiment of the invention is shown, in which like reference numerals designate the same components as in Figures 1 and 2. This second embodiment of the invention differs from the first only in that the inflow of the suspension from the suspension distribution pipe 26 takes place via the suspension outlets 28 into second lamella annular spaces 31b , which are delimited at the bottom by a short lamella 30a and at the top by a long lamella 30b . Accordingly, the flow of the clarified fluid from the separation chamber 32 is effected in the first annular plate spaces 31a, which are bounded by a long blade 30b and the top of a short blade 30a respectively below.

Due to this difference, the main flow of the Kl-r-fluid down and thus against the main flow of solids, dissolved and partially dissolved substances, which takes place up to the Flotatsammelraum 34 out. As a result of this countercurrent and the turbulences generated therewith, a better degree of separation results for special suspension compositions than with the embodiment according to FIGS. 1 and 2.

The invention is preferably used in the treatment of water in paper mills or sewage treatment. The suspension contains, for example, as solids: fibers, mineral particles or microorganisms, as partially dissolved substances colloidal substances, fats, color pigments and as solutes carbon hydrates, salts, organic or inorganic acids.

Claims (16)

1. A flotation device for separating materials or mixtures of materials from suspensions to form at least one high material content fraction and one low material content fraction, with several rotationally symmetrical plates arranged one above another in a flotation tank, wherein during the separating procedure, the low material content fraction enters into plate spaces between the plates and arrives at a clarified fluid collecting tube, wherein horizontally outside the plates, a vertically extending annular separating space is formed that communicates with a run-off for the high material content provided above the plates, characterised by
   a reaction and mixing space (18) with eccentric inlet (16) for mixing the suspension particles with gas bubbles and for further conveyance into at least one centrally arranged vertical suspension distribution tube (26);
   wherein the suspension distribution tube (26) and the clarified fluid collecting tube (48) are arranged adjacently;
   the plates (30) surround the suspension distribution tube (26) and the clarified fluid collecting tube (48) in an annular manner;
   every second annular plate space (31) between adjacent plates (30) is connected to the suspension distribution tube (26) and every other space between plates (31) is connected to the clarified fluid collecting tube (48), so the flow takes place from one space between plates (31) from the inside to the outside towards the separating space (32) and subsequently into an adjacent space between plates (31) from the outside to the inside.
2. The flotation device as set forth in claim 1, characterised in that the plates (30) and/or the flotation tank (12) are configured round or regularly polygonal.
3. The flotation device as set forth in claim 2, characterised in that the plates (30) are configured substantially conically or, conversely, pyramid-shaped.
4. The flotation device as set forth in claim 3, characterised in that the plates (30) are inclined upwards in the radial direction.
5. The flotation device as set forth in claim 1, characterised in that in the radial direction, shorter plates (30a) and longer plates (30b) are arranged alternately one above another.
6. The flotation device as set forth in claim 5, characterised in that a first annular plate spacing (31a) formed below by a longer plate (30b) and above by a shorter plate (30a) is connected to the suspension distribution tube (26) and a second annular plate spacing (31a) formed below by a shorter plate (30a) and above by a longer plate (30b) is connected to the clarified fluid collecting tube (48).
7. The flotation device as set forth in claim 5, characterised in that a second annular plate spacing (31b) formed below by a shorter plate (30a) and above by a longer plate (30b) is connected to the suspension distribution tube (26) and a first annular plate spacing (31a) formed below by a longer plate (30b) and above by a shorter plate (30a) is connected to the clarified fluid collecting tube (48).
8. The flotation device as set forth in claim 5, characterised in that the shorter plates (30a) are 5% to 40% shorter in the radial direction than the longer plates (30b).
9. The flotation device as set forth in claim 5, characterised in that the separating space (32) between the ends of the plates (30) and the wall of the flotation tank (12) has an extent between 10% and 30% of the extent of the longer plates (30b) in the radial direction.
10. The flotation device as set forth in claim 1, characterised in that the inclination of the plates with respect to the horizontal is between 10° and 60°, preferably between 30° and 50°.
11. The flotation device as set forth in claim 1, characterised in that arranged centrally in the flotation tank (12) is a conduit comprising both the at least one suspension distribution tube (26) and the at least one clarified fluid collecting tube (48).
12. The flotation device as set forth in claim 11, characterised in that the conduit is divided into at least two sector-shaped conduits, one of which sector-shaped conduits forms the suspension distribution tube (26) and the second sector-shaped conduit of which forms the clarified fluid collecting tube (48).
13. The flotation device as set forth in claim 12, characterised in that the conduit is divided into 4 to 8, preferably 6 sector-shaped conduits, wherein the suspension distribution tubes (26) and clarified fluid collecting tubes (48) alternate circumferentially.
14. The flotation device as set forth in claim 11, characterised in that in the conduit, horizontal throughflow slots (28, 46) are configured approximately the width of the sectors for discharge of the suspension from the suspension distribution tube (26), and for letting in the clarified fluid into the clarified fluid tube (48) into and respectively out of the associated annular plate spaces (31).
15. The flotation device as set forth in claim 1, characterised in that the reaction and mixing space (18) is configured as a double cone, wherein the upper cone merges into the at least one suspension distribution tube (26) and the lower cone into a sediment drain (20).
16. The flotation device as set forth in claim 1, characterised in that it includes a base unit, a lid unit and several plate units that can be assembled vertically one above another, wherein each plate unit includes distribution and collecting tube sections, annular space external wall sections, and several plates (30).

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